Electronic programmer for machine-control systems having simultaneous plural inputs

ABSTRACT

An electronic programming arrangement for machine operation in a system in which a switch arrangement has a condition in which it represents a predetermined prior condition and is adapted to control an element, e.g. relay, electromagnetic valve or motor. The system has an amplifying transistor and circuitry for maintaining the transistor normally at a predetermined bias; the transistor being effectively connected with the machine-control element for operation thereof only upon the attainment of a predetermined operating bias. The switch arrangement includes a plurality of resistors in circuit with the transistor and the respective switch, each of which must be rendered effective before the transistor initiates the control operation. The switch arrangement may include a set of switch contacts in circuit with a DC source and the resistors in a crossbar array while the transistor operatable by each set of switches becomes effective only when all of them have been set in a predetermined condition. The transistor serves as the input to a bistable switch device (e.g. a multivibrator flip-flop) which can operate an output transistor arrangement as part of a switch system with similar crossbar arrays of resistors. A time delay network is provided between each of the transistors and the respective bistable multivibrators.

United States Patent {72] inventors Weilheim; Egon Penzkofer, Munich, both of, Germany [2|] Appl.No. 764,153 {22} Filed Oct. 1,1968 {45] Patented July 13,1971 [73] Assignee Krauss-Maflei Aktiengescellschaft Munich-Allah, Germany [32] Priority Oct. 3, 1967 [33] Germany [311 P15 88374.6

[54] ELECTRONIC PROGRAMMER FOR MACHINE- CONTROL SYSTEMS HAVING SIMULTANEOUS PLURAL INPUTS 16 Claims, 7 Drawing Figs.

[52] U.S.Cl 340/147, 340/149, 340/166, 340/172 [51] lnt.Cl H04q 1/00 [50] FieldofSenrch 340/166, 172, 149, 147

[ S 6] References Cited UNITED STATES PATENTS 2,627,039 l/1953 Macwilliams 340/166 2,869,110 1/1959 Wagner 340/172 3,168,722 2/1965 Sanders 340/172 3,312,941 4/1967 Booth 340/166 e r n 4 1 21 z E MK 3 'k MK FR 20 a TD 7 5 a a 3 1 A D 16 n -w 1 1 1 W725 6 1 g 8 3 Wk w 5% 8H 3 l l. T

- 1 l f i l :24 l

1 I r f l 118 I r 3 3s 32 3,1 "30 i Y l a Q a r; r. i l I k i g l l l Gerhard Lerch 3,402,392 9/1968 Schroeder Primary Examiner- Harold l. Pitts Attorney-Karl F. Ross ABSTRACT: An electronic programming arrangement for machine operation in a system in which a switch arrangement has a condition in which it represents a predetermined prior condition and is adapted to control an element, e.g. relay, electromagnetic valve or motor. The system has an amplifying transistor and circuitry for maintaining the transistor normally at a predetermined bias; the transistor being effectively connected with the machine-control element for operation thereof only upon the attainment of a predetermined operating bias. The switch arrangement includes a plurality of resistors in circuit with the transistor and the respective switch, each of which must be rendered effective before the transistor initiates the control operation. The switch arrangement may include a set of switch contacts in circuit with a DC source and the resistors in a crossbar array while the transistor operatable by each set of switches becomes efiective only when all of them have been set in a predetermined condition. The transistor serves as the input to a bistable switch device (e.g. a multivibrator flip-flop) which can operate an output transistor arrangement as part of a switch system with similar crossbar arrays of resistors. A time delay network is provided between each of the transistors and the respective bistable multivibrators.

PATENTEUJuumsn 3593289 A SHEET 3 OF 3 FIG. 5 W

CCID

Gerhard Larch gvn Penzkofer INVEN'I'URS.

BY 8 M Attmey ELECTRONIC PROGRAMMER FOR MACHINE- CONTROL SYSTEMS HAVING SIMULTANEOUS PLURAL INPUTS i Our present invention relates to a programming arrangement for machine-control systems adapted to be used for the initiation of the sequenceof machine-operating steps of the type which have been directed heretofore by sequencing, limit and position-detection switches; more particularly this invention relates to a circuit arrangement for the electronic control of sequential machine operations.

It has become common practice in complex machinery to provide programming arrangements in the form of sequencing devices, limit switches and position-detecting elements which are adapted to trigger successive steps in a machine-operating cycle. The machine control is affected by various electrical elements, e.g. relays, servomotors, electromagnetically operated valves for hydraulic and pneumatic control elements or the like. In a typical arrangement of this kind, for example an injection-molding machine for the high-rate production of thermoplastic articles, a plasticizing screw is driven to feed the thermoplastic material to an injection chamber, the mold halves are brought together by hydraulic or pneumatic cylinders, the injection ram is driven forwardly to force the plasticized resin into the mold, the ram may be withdrawn, the mold halves are retracted to release the molded article with or without the advance of a knockout-in pin arrangement, and the mold is thereafter closed after a safety switch arrangement has indicated that the previously formed article has been entirely ejected. The sequence of this machine is controlled by limit switches in the path of the mold slides, pressure-responsive switches, electromagnetic valves which are operated by such switches or optical devices (photocells), by contacts along the guide rails or by switch contacts provided on switch .or-programming discs or drums when the position-detection system includes rotating elements.

In machines of this type, a large number of interdependent series-connected switches must be provided so that each set initiates a subsequent operation. For example, it has been necessary heretofore to connect a switch indicating complete discharge of the molded article, a pair of limit switches indicating total retraction of the mold, a limit or positionresponsive switch indicating full retraction of the knockout pins, a switch responsive to the presence or absence of thermoplastic resins in the injection chamber, etc. in series for the initiation of the mold-closing" step, an operation which may require only energization of two electromagnetic valves. These systems require sufficient space to allow the many switches to be mounted on the machine and involve time-consuming setting operations. Changes in the program of the machine are thus difficult and expensive.

It is, therefore, the principal object of the invention to provide an improved programming system for a multistep machine in which machine-control elements are operable in accordance with the settings of one or more switches representing the performance of preceding operations.

A more specific object of the invention is the provision of readily resettable programming means for a machine having a succession of operating steps and which requires little space, is relatively inexpensive and eliminates the need for many of the mechanical switching devices which have hitherto been necessary to carry out a considerable number of operations in sequence. Yet another object is the provision of an electronic programmer capable of the improved control of sequential operations.

These objects and others which will be apparent hereinafter are obtainable, in accordance with the present invention through the provision of an electronic control circuit arrangement cooperating with a switch arrangement responsive to a predetermined prior contact and settable by hand or automatically to represent this condition and capable of energizing one or more machine control elements to initiate the subsequent operation. The system of this invention includes transistor-amplifier means between the switch arrangement and the machine-control element (e.g. an electromagnetic relay and/or an electromagnetic valve, solenoid or other motor or operating mechanism), having a predetermined biasing condition which is altered by the operation of the switches to impart a biased level representing the attainment of the predetermined switch condition, whereby the output of the transistor serves to operate the control element only when all of the switches of the set have been properly prepared or actuated. The switch arrangement may be constituted by a set of mechanical or electronic switching devices operated byhand, or by portions of the machine directly or indirectly in accordance with one aspect of this invention. In this case, the transistor operated one or more bistable multivibrators (flipflops) which, in turn act as switching devices for triggering relays of a similar set of transistors which must reach the desired biased level to be rendered operative. In accordance with another aspect of this invention, the bistable multivibrator constitutes the switch arrangement which operates the transistors and, in turn, the relays.

According to an essential feature of this invention, each of the transistors is designedto be normally conductive and has a control element, e.g. the base, which is biased to reduce the conductivity of the transistor to zero when all of the switches necessary to the particular set are in an actuated condition; only then is the associated multivibrator triggered to produce the output which operates the associated relay. I

Still another important feature of this invention resides in the provision of a time-delay network between the transistor amplifier and the bistable multivibrator, the time-delay network being designed to prevent the transients normally generated in a switch-operated system from energizing the multivibrator prematurely.

According to a further, but important feature of this invention, the setting of the program is facilitated in a particularly convenient and inexpensive manner by constituting the switch arrangement as a resistance system adapted to cut in or out one or more resistances, connected with the respective switches upon operation of the latter.

Thus, when the transistors have their bases adapted to trigger the bistable multivibrators or the relay or other device controlling the machine, we provide each of the switches of a particular set in circuit with the base of the transistor and in parallel with one another, with a characteristic series resistance which, when cut in by the respective switch contacts, suffices together with the other resistors of the actuated switches of the set to bring the base of the transistor to the desired operating bias, preferably, a zero bias.

Advantageously, the resistors are connected in series with the respective switch, thebase of the transistor and one terminal of the DC source. The other terminal of the DC source is returned to the junction between the first mentioned resistor and the switch via a second resistor assigned to each switch. Since overlapping sets of switches are generally desired to operate one or more bistable multivibrators, we have found it to be advantageous to associate a respective one of these second resistors with each switch so that a series circuit is formed between the second resistors, the respective switch and the DC source while a plurality of first resistors connect the respective transistors with the switches between the latter and the second resistors. It has been found that these first resistors can be readily exchanged, replaced or repositioned to establish the desired program by forming a matrix of printedcircuit board or the like, preferably in the form of a crossbar plate, the first resistors being soldered to two intersecting bars so as to be readily insertable, removable or replaceable in accordance with the desired switching program.

As previously noted, one or more of the multivibrators may be connected to operate each of the machine-controlling elements in a predetermined set. Advantageously, this programming arrangement also makes use of a resistance-switch arrangement wherein the bistable multivibrators constitute the switches and are connected in circuit with respective resistances to the bases of corresponding transistors which are brought to a predetermined bias to initiate operation of the control elements (i.e. a relay). In this case, a similar crossbar arrangement is provided between the output side of the multivibrators and the corresponding output transistors to enable the resistors to be rapidly inserted and removed, thereby facilitating the setting of the program.

The invention also provides for a unit construction or component system, mounted upon a single printed circuit board and including the input transistor, its time delay network, its bistable multivibrator, and the corresponding output transistor, the printed circuit board having plugs enabling connection of the device to the input and output resistor matrixes and to the set of switches designed to control this unit. It is often convenient to mount the relay as well upon this printed circuit board and provide switch contacts to the control devices (electromagnetic valves) of the machine.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is an overall schematic diagram of a system embodying the present invention;

FIG. 2 is a circuit diagram of a transistor amplifier at the input side of the system, according to the present invention, illustrating its relationship with the respective set of switches;

FIG. 3 is a circuit diagram of the output transistor arrangement according to the invention showing the relationship of the transistor amplifier with the relay controlled thereby;

FIG. 4 is a circuit diagram of an electronic switch adapted to be used at the input side of the system;

FIG. 5 is a circuit diagram of an electric relay or switch operation without mechanical contacts for controlling the machine element (i.e. an electronic valve);

FIG. 6 is a circuit diagram of a component of the system of the present invention including input transistors, multivibrator, output transistor and relay; and

FIG. 7 is an elevational view of a crossbar arrangement according to the present invention.

In FIG. 1 of the drawing, we have shown a machine control system having hand-actuated position-responsive switches 1- 4 and an electronic switch which is represented diagrammatically at 5 but can be a mechanical switch 5a or the electronic switch illustrated in FIG. 4.

The switches 1-4 may be operated by the control machine, eg an injection-molding-machine slide, as so called limit switches at the end of the slide travel or as contacts in a rotary position-indicating system of the type described, for example, in Servomechanism Practice, McGraw-Hill Book Company, New York, 1960. The system of FIG. 1 controls machineoperating elements such as fluid-control valves (electromagnetically operable) or servomotors of any desired type. Typical control elements of this character are described in Perry's Chemical Engineers Handbook, McGraw-Hill Book Company, New York, I963 and Marks Mechanical Engineers Handbook, McGraw-Hill Book Company, New York, 1958. When reference is made hereinafter to switches settable to operate the device, therefore, it is to be understood that these switches may be provided with mechanical contacts or may be,

contactless (electronic) and that the control elements may include devices other than electromagnetic valves in spite of the fact that only these may be specifically mentioned.

As can be seen from FIG. 1, each of the switches 1-5 is connected in series with a DC source represented at the terminals S' and S" and constituting the positive and negative terminals of the system, respectively. Between the switches 1-5, which are tied to the negative terminal S", and the positive terminal 5' of the bus bars 16 and 17, we provide respective resistors 11, 12, 13, 14, and 15. Each switch combination or set of switches 1-5 is associated with a transistor amplifier A as represented at 18-23 in series with a time-delay network 24-29 represented by the box TD. The sets of switches 1-5 are determined by the connections of resistors 41 as will be apparent hereinafter and six sets can be discerned, Set I for example which operates the transistor amplifier 18 includes switches 1, 3, and 5 while set II of transistor amplifier 19 is operable by switches 1 and 4 together with an electronic switching arrangement constituted by the bistable multivibrator 42 of switch set I. Similarly, switch set 111 is formed by switches 1 and 2 together with the multivibrator 42, while switches set IV includes switches 1, 3, 5 and the multivibrator 43 associated with switch groups 11 and III. Switch group V includes switches 2 and 4 and the multivibrator 43 while switch group Vl is formed by switches 4, 5 and the multivibrator 43.

The conductors 30-34 between switches 1-5 and the cor responding resistors 11-15 are orthogonal to the parallel conductors 35-40 which are connected to the bases of the transistor amplifiers 18-23 so that the conductors 30-34 and 35-40, define a crossbar array which is represented generally at and is structurally illustrated in FIG. 7. This resistor matrix includes resistors 41 at each of the intersections at which a junction is desired. The resistors are arranged at the intersections in accordance with the control program so that for the switch group I in which switches 1, 3, and 5 are to operate the transistor 18, three resistors 41 are provided at the intersections of lines 30 and 35, lines 32 and 35, and lines 34 and 35, respectively. Similarly, switch group IV additionally has a resistor 41 connecting a line 60 parallel to the lines 30- 34 and coupled with the multivibrator 43, with the line 38 while lines 30, 32 and 34 are linked at the corresponding intersections with line 38 by additional resistors 41.

The resistance arrangement is dimensioned so that, when all of the switches l, 3, and 5 of group I, for example, are energized the line 35 is brought to zero potential and operation of the transistor 18 is permitted. The transistor 18, as mentioned earlier, is connected with the time-delay network 24 of the R- C-type (resistance-capacitance) and designed to introduce a delay of about 10 milliseconds prior to passage of a positive potential to trigger a corresponding bistable multivibrator or flip-flop 42 which is brought into its on" condition. A positive potential is thereby generated at the line 43 of an output crossbar array 12.

The output crossbar array 12' includes parallel conductors 45-47 connected respectively to the bistable multivibrator 42 operated by the group I switches, the bistable multivibrator 43 operated by the switches of group II and group III jointly, and the bistable multivibrator 44 operated by the switches of groups IV-VI, jointly. Additional conductors 63 and 64 are associated with manually operable switches 61 and 62 which will be described in greater detail hereinafter.

Since it is desired that the switching arrangements 42-44, 61 and 62 operate the output elements (i.e. relays 6-10) in accordance with a predetermine grouping or program, resistors 48 are provided at the desired intersections of the parallel conductors 54-58 (orthogonally intersection the conductors 45-47, 63 and 64) and connected with the transistor amplifiers A represented at 49-53, respectively. These transistor amplifiers are designed to energize the relays 6-10 which are returned to the negative terminal S. Consequently, when the bistable multivibrator 44 is energized, it can enable, via line 45 and the corresponding resistors 48, the amplifiers 50, 52 and 53 which are placed in operation when switch 62 is operated, when multivibrator 43 is triggered and when both switch 62 and multivibrator 44 are energized, respectively. Operation of the transistors 50, 52, and 53 results in energization of the relays 7, 9, and 10 to, in turn, provide the next machine-controlling function.

Both transistor amplifiers 19 and 20 serve to operate the single multivibrator 43 via the respective time-delay networks 25 and 26. The three amplifiers 21-23 trigger the bistable multivibrator 44 via the corresponding time-delay networks 27-29. Further output transistor amplifiers 49 and 51 cooperate with respective lines 54 and 56 which are enabled by the bistable multivibrators 43 and 44. The resistors 48 bridge the desired intersection points of the lines 54-58 and 45-47, 63, and 64 to establish the control program.

In the case in which the on" condition of multivibrator 44 i is the first step in the process, a line 59 allows it to enable the second step by multivibrator 43, the line 59 being connected by appropriate resistors 41 to the transistor amplifiers 19 and 20 as part of the switch sets II and III described earlier. In the system illustrated in FIG. 1, two starting relationships are possible for multivibrator 43. In the first case, switches I and 4 can be actuated while in the second case switches 1 and 2 can be triggered. In other words, switch groups II and III are both enabled by the multivibrator 42 but only one group need be completely activated to operate multivibrator 43 and initiate the second stage of the process. Multivibrator 43 may also enable the relays 6 and 8 via the output transistors 49 and 51 as previously discussed. The third stage of the machine operation makes use of the multivibrator 44 in the manner previously described, this multivibrator being enabled by the multivibrator 43 via line 60.

Manually operable switches'6l and 62 may be provided to allow control of the relay 7- or 6, 8, and 9 via lines 63 and 64 by hand for either cutting out machine operations or rendering additional operations possible. Whether such manually controlled switches are provided or not, we provide each of the prior operating multivibrators 42, 43, etc. with an output adapted to enable a succeeding multivibrator stage and thus constituting part of theswitch arrangement therefor.

In FIG. 2 we show a transistor stage which, for example, may represent that illustrated at 18 in FIG. I. Here a mechani cal switch 5a is shown in place of electronicswitch 5. The

reference numerals used here are, of course, identical to those used in FIG. 1. The time delay network 24 of this circuit is illustrated as a resistance-capacitance arrangement of resistor 72 and capacitor 71 connected across the emitter-collector electrodes of the transistor 18 with an output resistor-70 tied between the resistor 72 and the capacitor 71 so that at point 70, an output is obtained for triggering the bistable multivibrator 42 (see FIGS. 3 and 6 for the circuit relationship of the multivibrator). The circuit arrangement of FIG. 2 includes resistors ll, 13, and IS in series with the switches l, 3 and 50 across the bus bars 16 and 17 of the positive and negative terminals, respectively. The base bias of the transistor 18 is established by an emitter-base resistance 18' and a base-collector resistance system constituted by the resistors 1 l, l3, 15,-

41, and 18". The base of transistor 18 thus has three resistors 41 connected in parallel which are short-circuited to the negative potential by the switches 1, 3, and 50 when they are closed. The resistors 41 are in series with the base terminal of the transistor and the respective resistors 11, I3, and 15 with respect to the connection to the positive bus bar 16.

The resistors II, l3, l5, and 41 are so'dimensioned that the transistor 18 is only fully switched when each of the switches l, 3, and 5a is closed so that the open condition of any one of these switches 1, 3, and 50 will maintain a bias at the base of transistor 18 such that it is ineffective. Thus, when all of the switches I, 3, and 5a are closed, the base of transistor 18 is brought to a zero potential and a positive voltage develops at the collector and' transistor. After a delay of about l0 milliseconds, the positive potential builds up at the terminal 70 of the time delay network so that premature transient positive spikes are not applied to the bistable multivibrator 42 to which the transistor 18 is connected.

The number of possible resistors 41 which may be used for the operation of each transistor 18 will be dependent, of course, upon the nature of the transistor, the voltage which may be applied across it, and sensitivity of the transistor circuit. Since the number of resistors 41 will also determine the control function which may be performed by a particular network, it is desirable to have the highest number possible according to the present invention. We have found that with silicon transistors which are operable at high voltages, it is possible to use a potential of 24 volts across the bus bars 16 and I7 and thus employed 24 resistors 11; I3, 15 and 4!. Furthermore, the resulting high number of control functions has been found to be particularly convenient for even the most complex operations such as the programming of injection molding machines.

In FIG. 3, we have shown the output transistor arrangement of the system of FIG. 1 in greater detail.

The output sides of multivibrators 42 and 44 are represented by transistors 42a and 44a, respectively, having the resistors and 81 connected in the emitter-collector networks across the DC source represented by bus bars 16 and 17. As described in greater detail in FIGS. 1 and 2, the sequence-control and selection resistors 48 at the output side of the system are tied in parallel with one another to the junctions of the resistors 80 or 81 with respective collectors of the transistors 42a and 44a.

The resistors 48 are, together with the resistors 80 and 8 1 (corresponding to resistors ll, 13, etc.) connected between the positive bus bar 16 and the base transistor 53(The control base bias is applied by a resistor 53" connected between the base and the negative bus bar 17. As soon as the bases of the output transistors 42a and 440 are rendered currentless, corresponding to the on" condition of the multivibrator, the base of output transistor 53 is energized via the resistors 48 to turn on the relay 10 and operate its switch 10' to control an electromagnetic valve or the like for initiating a subsequent machine operating step.

The output transistor 53, as described in connection with. amplifier transistors 18 -23 in FIG. 1,may cooperate with a multiplicity of resistors 48 to provide a large number of control functions and responses. Furthermore, the relay 10 can be controlled via further amplifier means so that two or more output matrices of resistors can be used to further increase the switching and programming possibilities.

In FIG. 4, we show the electronic switch which is represented at 5 in FIG. 1 and which can be substituted for any of the switches 1-4 as well. In this circuit, the transistor 85 is operated by a differentiation circuit or trigger network (Schmitt trigger) the former-being illustrated in FIG. 4 and including a capacitor 86 connected between the negative bus bar 17 and a bias resistor 85 of the transistor 85. The capacitor 86 is energized over a diode 91 from the induced potential over a magnetic detector represented at FIG. 4 as having an induction coil 87 surrounding a U-shaped magnetized yoke 89 with which the armature 88 cooperates.

When the tripper 88' (a spring tongue or the like) is engaged by a moving portion of the machine or a stationary portion when the switching device is shifted on a moving portion of the machine, the armature 88 is brought into contact to the yoke 89 to complete the magnetic circuit and to induce an electric current in the coil 87, the induced electric current being superimposed upon the AC energizing current applied at the terminals 88". A resistor 90 in series with the coil 87 acts as a current-limiting device. The resistor 90 is so dimensioned that the voltage drop through the induction coil 87 in the open magnetic circuit between yoke 89 and armature 88 is smaller than the through-flow potential of the diode 91 and the base-emitter network of the transistor 85; when the magnetic circuit is closed, however, the higher voltage drop is detected by the transistor 85, the emitter-collector network becomes conductive to connect the respective resistor 41 and resistor 15 in the control circuit as if a contact switch was provided.

As previously noted also, the mechanical-contact relays of FIG. 1 can be replaced by electronic switches, a suitable circuit of which is shown in FIG. 5. In this FIG., the electronic switch is a Triac double thyristor whose control element 95 is connected to the secondary winding of a current transformer 97 in series with the output transistor 98. The operating potential of transistor 98 can be an alternating current of intermediate frequency (30 kHz) superimposed upon the normal DC potential. The base-emitter bias is supplied by a resistor 98 while resistors 99 correspond to the resistances 48 of FIG.

I. When transistor 98 becomes conductive, a potential is ap-.

plied at 95' to the Triac device which is rendered conductive to operate the electromagnetic valve 96.

In FIG. 6, we have shown a circuit ofa control unit mounted upon a single printed-circuit board according to the present invention and having a multiterminal plug represented at 130 whereby the printed circuit unit can be incorporated in a machine control system. The control unit includes a pair of amplifier transistors 110 and 111 (corresponding to the transistors I8-23 of FIG. I), in circuit with respective timedelay networks 112 (corresponding to the networks 2429). Both of these amplifying transistors I10 and 111 are connected in parallel to a multivibrator indicated at 114, the output of which is applied to the output transistor 115 as described in connection with FIG. 3 for the output transistor 53. The collector-emitter network of the transistor 115 is connected in series with the relay coil I16, corresponding to one of the relays 6-10. The network of FIG. 6 thus combines in a single unit the structure represented in broken lines at Ila, 119 in FIG. I. As is customary in such components, the plug 130 can be mounted on the edge of a printed circuit board 118, 119. The relay 116, which advantageously has a switching capacity of amperes at about 220 volts, can also be mounted on the board which may have dimensions about 70 70 mm. 30 ofsuch printed circuit units have been found to be $atisfactorily for the complete control of an injection molding machine.

As can be seen from FIG. 7, the input and output resistor matrixes comprise a nonconductive etched or printed circuit board 131, preferably provided with plugs as illustrated in connection with FIG. 6 or with jacks to receive the plug 130 and has on its opposite sides the orthogonal arrays of mutually parallel but spaced-apart conductors I25 and 126. The latter are connected to leads 127 on the upper surface of the plate through holes 127' in the plate 131. At each of the intersections, additionally holes 128' are provided in which the resistors 128 are replaceably soldered to the conductors 125 and 126. The resistors I28, of course, represent the resistors 41 or 48 previously described. The conductors are formed by any of the conventional printed circuit techniques. Instead of plugs, the end portions 125a of the conductors 125 may serve as plugs cooperating with jacks of conventional construction adapted to receive same. To alter the program, it is merely necessary to unsolder the undesired resistance and replace it with another or move the release resistor to another intersection. The conductive plates are represented by the bold line borders in FIG. I as shown at 120 and 121.

The improvement described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the invention except as limited by the appended claims.

We claim:

1. A system for programming a machine to activate a plurality of machine-control elements in response to respective predetermined prior conditions, said system comprising:

a respective set of switching devices associated with each of said elements and operable in toto to initiate activation thereof while representing said condition, thereby initiating a machine operation;

respective transistor-amplifier means between each of said sets of switching devices and the respective element and effective upon the attainment of a predetermined bias condition to actuate said respective element;

circuit means normally maintaining said transistor-amplifier means under a bias other than said predetermined bias condition; and

respective means connected in circuit with each said transistor-amplifier means and the respective set and including respective bias resistors between the base of said transistor and said switching devices and effective only upon the attainment of said predetermined condition of said switching devices as represented by actuation of the entire set for applying said predetermined bias condition to said transistor-amplifier means, thereby activating the respective element.

2. The system defined in claim 1, further comprising a direct-current source, respective first transistors connected in series with each of said devices across said source, the respective first-mentioned resistors being connected between the base of said transistor and the respective switching device between the latter and the corresponding second resistor.

3. The system defined in claim 2, further comprising a crossbar matrix for said first resistors, said matrix comprising a plurality of mutually parallel transversely spaced conductors connected to the respective switching devices, and an orthogonal array of mutually parallel transversely spaced conductors respectively connected to the bases of corresponding transistors, said first resistors of said set of devices bridging the conductor associated with the respective transistor and the conductors associated with the respective switching device at the intersections of said conductors.

4. The system defined in claim 3 wherein said conductors are formed on the opposite sides of a nonconductive plate provided with holes at said intersections, said first resistors being removably soldered to said conductors through said holes.

5. The system defined in claim 2, further comprising at least one bistable multivibrator between each said transistor amplifier means and the respective said element for activating same.

6. The system defined in claim 5 wherein a plurality of bistable multivibrators is provided, each operable by corresponding transistors of said transistor-amplifier means to initiate successive machine operations, each of said multivibrators engaged in a presetting operation being connected to a transistor of said transistor-amplifier means of a successively operating multivibrator for enabling same.

7. The system defined in claim 6, further comprising a timedelay network between each of said transistors and the respective multivibrator for preventing premature energization thereof by electrical transients produced by said devices.

8. The system defined in claim 7, further comprising respective amplifying transistors connected in circuit with each of said elements and bias-resistor means connected between the respective multivibrator and the amplifying transistors of said elements for selectively energizing same in accordance with a predetermined program.

9. The system defined in claim 1 wherein at least one of the switching devices of each set is a bistable multivibrator, said transistor-amplifier means including a respective transistor associated with each set of switching devices and operable only upon the actuation of all of said devices to establish a prearranged condition of the respective set, said transistor being connected with a respective element for actuating same.

10. The system defined in claim 9, further comprising a crossbar matrix for said bias resistors, said matrix comprising a plurality of mutually parallel transversely spaced conductors connected to the respective switching device and an orthogonal array of mutually parallel transversely spaced conductors respectively connected to the bases of the corresponding transistors, said resistors of each set of said devices bridging the conductor associated with the respective transistor and the conductors associated with the respective switching devices at the intersection of said conductors.

11. The system defined in claim 10 wherein said conductors are formed on the opposite sides of a nonconductive plate provided with holes at said intersections, said resistors being removably soldered to said conductors through said holes.

12. The system defined in claim 10 wherein at least one of the switching devices of each of said sets is a manually operable switch settable to enable the operation of the respective transistor.

13. The system defined in claim 12 wherein some of said bistable multivibrators are adapted to initiate operations subsequent to the operations of prior-operating bistable multivibrators, said prior-operating bistable multivibrators being connected to the subsequently operating multivibrators for enabling same.

14. The system defined in claim 13 wherein:

a plurality of input switching devices is provided in sets operably to initiate a succession of machine operations;

being connected to at least one of said bistable multivibrators for energizing same.

15. The system defined in claim 14, further comprising time-delay means between each of said input transistors and the respective bistable multivibrator.

16. The system defined in claim 15 wherein each of said multivibrators, an amplifier transistor energized thereby, a respective time-delay network and at least one input transistor form a plug-in circuit component assemblable in said system 

1. A system for programming a machine to activate a plurality of machine-control elements in response to respective predetermined prior conditions, said system comprising: a respective set of switching devices associated with each of said elements and operable in toto to initiate activation thereof while representing said condition, thereby initiating a machine operation; respective transistor-amplifier means between each of said sets of switching devices and the respective element and effective upon the attainment of a predetermined bias condition to actuate said respective element; circuit means normally maintaining said transistor-amplifier means under a bias other than said predetermined bias condition; and respective means connected in circuit with each said transistoramplifier means and the respective set and including respective bias resistors between the base of said transistor and said switching devices and effective only upon the attainment of said predetermined coNdition of said switching devices as represented by actuation of the entire set for applying said predetermined bias condition to said transistor-amplifier means, thereby activating the respective element.
 2. The system defined in claim 1, further comprising a direct-current source, respective first transistors connected in series with each of said devices across said source, the respective first-mentioned resistors being connected between the base of said transistor and the respective switching device between the latter and the corresponding second resistor.
 3. The system defined in claim 2, further comprising a crossbar matrix for said first resistors, said matrix comprising a plurality of mutually parallel transversely spaced conductors connected to the respective switching devices, and an orthogonal array of mutually parallel transversely spaced conductors respectively connected to the bases of corresponding transistors, said first resistors of said set of devices bridging the conductor associated with the respective transistor and the conductors associated with the respective switching device at the intersections of said conductors.
 4. The system defined in claim 3 wherein said conductors are formed on the opposite sides of a nonconductive plate provided with holes at said intersections, said first resistors being removably soldered to said conductors through said holes.
 5. The system defined in claim 2, further comprising at least one bistable multivibrator between each said transistor amplifier means and the respective said element for activating same.
 6. The system defined in claim 5 wherein a plurality of bistable multivibrators is provided, each operable by corresponding transistors of said transistor-amplifier means to initiate successive machine operations, each of said multivibrators engaged in a presetting operation being connected to a transistor of said transistor-amplifier means of a successively operating multivibrator for enabling same.
 7. The system defined in claim 6, further comprising a time-delay network between each of said transistors and the respective multivibrator for preventing premature energization thereof by electrical transients produced by said devices.
 8. The system defined in claim 7, further comprising respective amplifying transistors connected in circuit with each of said elements and bias-resistor means connected between the respective multivibrator and the amplifying transistors of said elements for selectively energizing same in accordance with a predetermined program.
 9. The system defined in claim 1 wherein at least one of the switching devices of each set is a bistable multivibrator, said transistor-amplifier means including a respective transistor associated with each set of switching devices and operable only upon the actuation of all of said devices to establish a prearranged condition of the respective set, said transistor being connected with a respective element for actuating same.
 10. The system defined in claim 9, further comprising a crossbar matrix for said bias resistors, said matrix comprising a plurality of mutually parallel transversely spaced conductors connected to the respective switching device and an orthogonal array of mutually parallel transversely spaced conductors respectively connected to the bases of the corresponding transistors, said resistors of each set of said devices bridging the conductor associated with the respective transistor and the conductors associated with the respective switching devices at the intersection of said conductors.
 11. The system defined in claim 10 wherein said conductors are formed on the opposite sides of a nonconductive plate provided with holes at said intersections, said resistors being removably soldered to said conductors through said holes.
 12. The system defined in claim 10 wherein at least one of the switching devices of each of said sets is a manually operable switch settable to enable the operation of the respective transistoR.
 13. The system defined in claim 12 wherein some of said bistable multivibrators are adapted to initiate operations subsequent to the operations of prior-operating bistable multivibrators, said prior-operating bistable multivibrators being connected to the subsequently operating multivibrators for enabling same.
 14. The system defined in claim 13 wherein: a plurality of input switching devices is provided in sets operably to initiate a succession of machine operations; said transistor-amplifier means includes a respective input transistor associated with each set of input switching devices and operable only upon the actuation of all of said input devices of the corresponding set to establish a prearranged condition thereof; and said means connected in circuit with said transistor-amplifier means comprises respective first input bias resistors between the base of each input transistor and the respective input switching device of the corresponding set for applying a predetermined bias condition to the respective input transistor, each of said input transistors being connected to at least one of said bistable multivibrators for energizing same.
 15. The system defined in claim 14, further comprising time-delay means between each of said input transistors and the respective bistable multivibrator.
 16. The system defined in claim 15 wherein each of said multivibrators, an amplifier transistor energized thereby, a respective time-delay network and at least one input transistor form a plug-in circuit component assemblable in said system. 